1. Field of the Invention
The present invention relates to a method and an apparatus for adhering a protecting tape to a front surface of a wafer such as a semiconductor wafer or the like used as a substrate of electronic devices.
2. Description of the Related Arts
A semiconductor chip in which an electronic circuit such as an IC, an LSI or the like is formed in a front surface thereof is manufactured via a process of comparting lattice-shaped rectangular areas on the front surface of a disc-shaped semiconductor wafer by cut lines called streets, forming an electronic circuit in the rectangular areas and thereafter dividing the semiconductor wafer along the streets.
In the manufacturing process mentioned above, in the semiconductor wafer, a rear surface in an opposite side to a device surface in which the electronic circuit is formed is cut in accordance with a grinding by a grinder, or by device of a chemical etching, before the semiconductor wafer is divided into the semiconductor chips, whereby an entire thickness is reduced. Making the semiconductor wafer thin as mentioned above aims to improve a heat dissipation performance so as to maintain a performance in addition to making a device itself mounting the semiconductor wafer thereon thin or compact, or light in weight, and is executed, for example, to a thickness equal to or less than 200 to 100 μm or equal to or less than 50 μm, from an original thickness of 600 μm.
In this case, when making the semiconductor wafer thin as mentioned above, a protecting tape is adhered to the front surface of the semiconductor wafer for protecting the electric circuit on the front surface from contamination and damage. A technique to adhere the protecting tape mentioned above to the semiconductor wafer is disclosed, for example, in Japanese Unexamined Patent Publication No. 2001-148412 (paragraphs 0041 to 0049 and the like).
The technique described in this document is structured such that a protecting tape wound around an installation roll is draw out while detaching a liner paper therefrom, first an adhesive surface of the protecting tape is attached to an adhering table while keeping an expanded condition. Then, a non-adhesive surface of the protecting tape is adsorbed by an adsorption table, and the protecting tape adsorbed by the adsorption table is cut into a predetermined size and shape. Next, the cut protecting tape is adhered to a wafer within a vacuum chamber.
In the prior art described above, since the protecting tape is applied to the wafer in vacuum, bubbles are not remained between both the elements and generation of wrinkle can be inhibited. However, in the above technique, the protecting tape keeps the extended condition in which the protecting tape is drawn out from the installation roll after it was drawn out from the installation roll and attached to the adhering table till it is adhered to the wafer. In the extended condition, tensile force is applied to the protecting tape, and stress to contract to be free condition remains. If the protecting tape in this condition is adhered to the wafer and a thinning process is applied thereto as mentioned above, a warp is generated in the wafer by a tensile force of the protecting tape, and there is a risk that the wafer is broken in some cases.
Pre-dicing method is applied for a manufacturing method of a semiconductor chip in stead of the above mentioned general step in which a wafer is divided into chips after thinning the wafer. The pre-dicing method is performed by forming cuts in a lattice shape on the front surface at about a half of the thickness along the street comparting the formed electronic circuit, thereafter applying the protecting tape to the front surface thereof, and next cutting the back face in accordance with the grinding or the like till reaching the cut. In the case of employing the manufacturing method mentioned above, an adhesive bonding film (for example, a die attach film (DAF)) for mounting the semiconductor chip to the substrate is applied to the rear surface of the semiconductor wafer in a condition in which the divided individual semiconductor chips are coupled by the protecting tape, and only the adhesive film is thereafter cut along the street.
In the case of employing the method mentioned above, if the protecting tape to which the tensile force is applied as mentioned above is attached to the semiconductor wafer, a disarrangement is generated in the lattice-shaped array of the semiconductor chips due to the tensile force of the protecting tape, at a time of cutting the rear surface till reaching the cut and dividing into the semiconductor chips. In this case, since the cut line is not formed as a straight line but is formed as a distorted shape at a time of thereafter cutting the adhesive bonding film, it takes a lot of trouble with cutting and a reduction of a production efficiency is caused.